1. Field of the Invention
This invention relates to apparatus for transferring articles between conveyors and more particularly relates to apparatus in which packaged articles are transferred laterally from a first conveyor through a wrapping and sealing station for subsequent heat shrinkage of said wrapped packages. Such wrapping, sealing and heat shrinkage is known in the art as secondary wrapping.
2. Description of the Prior Art
Apparatus for transferring articles or packages from a first conveyor laterally through a wrapping and sealing station are well known in the art. However, in recent years there has been a marked increase in the demand for the wrapping of relatively thin packages and this has posed problems with regard to the stability of such packages during transit between adjacent conveyors.
More particularly, with the advent of small, thin, rectangular packages containing soft drinks or milk or the like, a need has existed for an efficient apparatus for shrink wrapping a unit of three rectangular packages together with a drinking straw.
In the prior art apparatus, units comprising three or more packages have been pushed laterally relative to the direction of movement of the packages on a first conveyor. This lateral pushing of the packages deposits the packages at the first station whereat the packages are encircled by a thin film of heat shrinkable plastics material. The thin film is then sealed to provide a loose tubular wrapping around the unit of packages. A subsequent unit of packages pushed laterally from the first conveyor contacts the previously wrapped unit of packages and urges the same laterally relative to the first conveyor onto a second conveyor for conveying the wrapped packages to a heat shrinking oven which heat shrinks the thin tubular film of plastics material around the unit of packages together with a drinking straw.
Serious problems have existed in the prior art apparatus in that as the wrapped unit of packages is urged onto the second conveyor, there exists a very real possibility that such unit of packages may topple onto the second conveyor rather than remaining in a balanced, upended disposition.
Furthermore, lateral orientation of the individual packages within a wrapped unit can occur, giving rise to an irregularly heat shrunk unit emerging from the heat shrinkage oven.
Additionally, in view of the relatively unstable configuration of the packages to be wrapped and heat sealed, there has been a need in the art for apparatus that would positively support packages during transit through the wrapping and sealing station.
The sequential feeding of individual packages along the first conveyor in order to be pushed laterally through the wrapping and sealing station has also given rise to problems in the prior art apparatus. Such problems arise in the event of one or more packages toppling from an upended position to a prostrate position relative to the first conveyor or during movement of the packages along the conveyor. When a package assumes the prostrate position, the relative positions of adjacent and subsequent packages moving along the first conveyor are altered. If the alteration in respective positions of the packages is not quickly detected, the packages when pushed laterally relative to the first conveyor will be crushed and the operation of the machine will be terminated until the crushed package and contents are removed from the wrapping and sealing station.
Therefore, it is the primary object of this invention to provide an apparatus that overcomes the aforementioned inadequacies of the prior art apparatus and provides an improvement which significantly contributes to the stability of a unit of packages during transfer of the same between adjacent conveyors and for sensing the presence of one or more packages disposed on the first conveyor in a prostrate position.
Another object of the present invention is the provision of gripping arms for positively grasping the unit of packages during transit through a wrapping and sealing station.
Another object of the present invention is the provision of a pair of gripping arms for supportingly engaging a unit of packages during transfer of the packages from a first conveyor to an adjacent second conveyor.
Another object of this invention is the provision of pneumatic means for pivoting a pair of gripping arms from a first position in which the arms grasp a unit of packages to a second position in which the arms release the unit of packages.
Another objective of the invention is the provision of pneumatic means for moving the pair of gripping arms and grasped packages in a direction and at a speed substantially the same as that of the second conveyor.
A further objective of the present invention is the provision of a sensing device disposed adjacent the first conveyor for sensing the relative positions of adjacent packages moving along the first conveyor. The sensing device detects the presence of one or more packages disposed in a prostrate position and controls a gate disposed along the first conveyor to impede the flow of packages therealong.
Another object of the present invention is the provision of a buffer, the buffer being controlled in accordance with the gate to retract and return to an original position to correctly position respective adjacent packages prior to pushing of the packages transversely relative to the first conveyor.
A further object of the present invention is the provision of a bar disposed transversely relative to the second conveyor, the bar toppling the unit of heat shrink-wrapped packages onto a third conveyor which moves substantially parallel to the first conveyor.
The forgoing has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more pertinent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Particularly with regard to the use of the invention disclosed herein, this should not be construed as limited to apparatus for wrapping and sealing packages with a heat shrinkable plastic film but should include apparatus for transferring any article between adjacent conveyors or the like, particularly in the transfer of articles having a configuration that lacks inherent stability.